Adachi Keisuke, Fa Shixin, Wada Keisuke, Kato Kenichi, Ohtani Shunsuke, Nagata Yuuya, Akine Shigehisa, Ogoshi Tomoki
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P. R. China.
J Am Chem Soc. 2023 Apr 12;145(14):8114-8121. doi: 10.1021/jacs.3c01019. Epub 2023 Mar 28.
Chirality of host molecules can be induced and/or inverted by the guest molecules. However, the adapting chirality of hosts to the length of -alkanes remains a great challenge because -alkanes are neutral, achiral, and linear molecules, resulting in a weak interaction with most compounds. Herein, we report a system with chirality adapted to -alkane lengths, using a pillar[5]arene-based macrocyclic host, , which contains five stereogenic carbons and five terminal bromine atoms on each rim. The electron-rich cavity of could include -alkanes and the planar-chiral isomers sensitively inverted in response to the lengths of the complexed -alkanes. The inclusion of a short -alkane such as -pentane made more inclined to be in the -form, whereas the inclusion of long -alkanes such as -heptane made the -form more favorable. The difference in the stability of the isomers was supported by the crystal structures and the theoretical calculations. Furthermore, temperature drives the adaptive chirality of with -alkanes. An -alkane with middle length, -hexane, showed the dominance of the -form of at a higher temperature, whereas the -form was shown at a lower temperature.
主体分子的手性可由客体分子诱导和/或反转。然而，使主体的手性适应直链烷烃的长度仍然是一个巨大的挑战，因为直链烷烃是中性、无手性的线性分子，与大多数化合物的相互作用较弱。在此，我们报道了一个手性适应直链烷烃长度的体系，使用基于柱[5]芳烃的大环主体，其每个边缘含有五个手性碳和五个末端溴原子。的富电子空腔可以包含直链烷烃，并且平面手性异构体可根据络合直链烷烃的长度而灵敏地反转。包含短直链烷烃如正戊烷会使更倾向于呈形式，而包含长直链烷烃如正庚烷会使形式更有利。异构体稳定性的差异得到了晶体结构和理论计算的支持。此外，温度驱动与直链烷烃的适应性手性。中等长度的直链烷烃正己烷在较高温度下显示形式占主导，而在较低温度下显示形式。
